JPS61147232A - Liquid-crystal element - Google Patents

Abstract

PURPOSE:To prevent the generation of defective orientation by providing one substrate with an electrode, forming a flattening layer which covers the substrate and electrode, and arranging ferroelectric crystal in contact with the surface of the flattening layer. CONSTITUTION:An element 30 has substrates 31 and 32 using transparent plates such as a glass plate and a plastic plate and the ferroelectric crystal 33 is sandwiched between the both. Electrode lines 34 required to form a matrix electrode structure are arrayed in stripes on the substrate 31 and the substrate 31 itself and the orientation control film 36 covering the electrode lines are provided in the same structure with spacer members 38. In this case, an insulating material is filmed thickly over the entire surface of the substrate 31 provided with the electrode 34 by using a spinner coating method and specific lithography is employed to etch the element except the spacer members 38. Consequently, the orientation control film 36 and spacer members 38 are constituted in one body and this orientation control film 36 is formed as the flattening layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to liquid crystal elements such as liquid crystal display elements and liquid crystal optical shutter arrays, and more specifically to liquid crystal elements with improved display and driving characteristics by improving the initial alignment state of liquid crystal molecules. Regarding elements.

Conventional liquid crystal elements include, for example, M, 5chadt, and W.
, “Applied Physi” by Helfrich
cs Letters “Vo, 18, No, 4 (19
71, 2, 15), P, 127-128 “Volta
ge Dependent 0pticalActi
Vity of a Twisted Nematic
T N shown in LiquidCryst・al''
A device using a (twisted nematic) liquid crystal is known. This TN liquid crystal has a problem in that crosstalk occurs during time-division driving using an IJ electrode structure with high pixel density, so the number of pixels is limited.

Furthermore, a display element is known in which a switching element using a thin film transistor is connected to each pixel, and each pixel is switched. However, the process of forming the thin film transistor on the substrate is extremely complicated, and it is difficult to use a display element with a large area. There are some problems that make it difficult to create.

In order to solve these problems, Clark et al. announced a ferroelectric liquid crystal device in US Pat. No. 4,367,924. However, in order for this ferroelectric liquid crystal element to exhibit predetermined driving characteristics, the ferroelectric liquid crystal placed between a pair of parallel substrates must be in the two stable states described above, regardless of the applied state of the electric field. It is necessary that the molecules be in such a state that conversion between them can occur effectively. For example, in a ferroelectric liquid crystal having a chiral smectic phase, the liquid crystal molecular layer of the chiral smectic phase is perpendicular to the substrate surface, and therefore there is a region (monodomain) in which the liquid crystal molecular axes are arranged almost parallel to the substrate surface. needs to be formed. However, in conventional ferroelectric liquid crystal devices, the alignment state of the liquid crystal having such a monodomain structure was not necessarily formed satisfactorily.
The reality is that sufficient characteristics were not obtained.

In particular, as mentioned above, when the mud and refrigeration poles formed on the substrate are wired with high density, the resistance of the negative pole wire is reduced.
The electrode wire is relatively thick (e.g. 1000 Å to 3000 Å)
The film thickness is 100 mm between the surface of the substrate itself and the electrode surface.
The inventor's experiments have revealed that a large step of 0 Å or more is formed and that this step causes alignment defects in the ferroelectric liquid crystal.

Accordingly, an object of the present invention is to provide a ferroelectric liquid crystal element in which the occurrence of alignment defects is prevented.

Another object of the present invention is to provide a ferroelectric liquid crystal element in which pixels are formed at high density.

Furthermore, another object of the present invention is to improve the monodomain formation or initial orientation that has been a problem in conventional ferroelectric liquid crystal devices, thereby improving the high-speed response inherent in ferroelectric liquid crystal devices. The object of the present invention is to provide a ferroelectric liquid crystal element that can fully exhibit memory effect characteristics.

As a result of further research for the above-mentioned purpose, the present inventors focused on the initial orientation in the cooling process in which liquid crystals transition from the isokyoshi phase (high-temperature state) to the liquid crystal phase (low-temperature state). It has now become possible to provide a liquid crystal element having a structure that is compatible with the operating characteristics of the element based on properties and the monodomain properties of the liquid crystal layer. That is, the liquid crystal element of the present invention is based on such knowledge, and more specifically, by eliminating steps on the surface in contact with the liquid crystal layer, that is, by preventing sudden changes in the thickness of the liquid crystal layer. It is characterized in that the initial orientation during the temperature cooling process is in a good state, and a monodomain with no orientation defects is formed. Therefore, the present invention is characterized in that a ferroelectric layer is formed between a pair of parallel substrates. In the liquid crystal element having a ferroelectric liquid crystal, at least one of the pair of parallel substrates has an electrode and a flattening layer covering the substrate and the electrode, and the ferroelectric liquid crystal is It is characterized by a liquid crystal element placed in contact with the surface of the flattening layer. In this way, the liquid crystal layer sandwiched between substrates with good planarity changes from the isokyoshi phase to the liquid crystal phase.During the cooling process, the liquid crystal phase region gradually expands to form a monodomain liquid crystal phase. Become.

For example, the above-mentioned DOBA exhibiting a ferroelectric liquid crystal phase as a liquid crystal.
Taking MBC as an example, when cooling slowly from the Tokichi phase of DOBAMBC, it undergoes a phase transition to a smectic human phase (SmA phase) at about 115°0.

At this time, rub the board or 8i0! When alignment treatment such as oblique vapor deposition is performed, monodomains are formed in which the molecular axes of liquid crystal molecules are parallel to the substrate and aligned in one direction. Furthermore, as cooling progresses, a phase transition occurs to the chiral smect C phase (SmC" phase) at a specific temperature between approximately 90 and 75 degrees Celsius, which depends on the thickness of the liquid crystal layer. When it is about 2μ or less, the helix of the SmC'' phase is unraveled and exhibits bistability.

Particularly suitable liquid crystal materials for use in the present invention are liquid crystals having bistability and ferroelectricity. Specifically, in addition to the above-mentioned SmC, chiral smectate ), I phase (SmI”), J phase (Sm
A liquid crystal having a phase K (SmK"), a phase G (8mG'), or a phase F (SmF") can be used.

For more information on ferroelectric liquid crystals, see e.g. Lg JO
URNAL DE PHYSIQUIDLETTB
R836 (L-69) 1975, “Ferroelec
tric Liquid Crystals J ;“
Applied Physics Letters”
36 (11), 1980 “Submicro 5
econd B15table Electroopt
ic Switching in LiquidCry
stals J; “Solid State Physics” 16 (141) 19
811'-Liquid Crystal,'' etc., and the ferroelectric liquid crystal disclosed in these documents can be used in the present invention.

Specific examples of ferroelectric liquid crystal compounds include decyloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC) and hexyloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC).
P'-amino-2-chloropropylcinnamate (HO
BACPC), 4-O-(2-methyl)-butylresol silidan-4'-octylaniline (MBRA8).

When constructing an element using these materials, the element can be supported by a block with a heater embedded, etc., as necessary, in order to maintain the temperature at which the liquid crystal compound enters the chiral smectate phase. .

The present invention will be explained below with reference to the drawings.

FIG. 1 shows a cross-sectional view of a conventional ferroelectric liquid crystal device, and FIG. 2 shows a state of alignment defects that appear in the conventional ferroelectric liquid crystal device.

That is, the conventional ferroelectric liquid crystal element 10 shown in FIG. 1 has a pair of parallel substrates 11 and 12, and the substrates 11 and 12 have striped electrode lines 13 and 14 forming a matrix electrode structure, respectively. is provided. These striped electrodes 1513 and 14 are generally made of ITO (In
For example, the electrode wire is made of a transparent conductive film such as 16 pet
(16 wires/mm), the line width of the electrode wire becomes extremely thin and the resistance becomes high. In order to lower the resistance, it is necessary to set the resistance to about 100OA to 3000λ.

Therefore, in a liquid crystal element with high-density pixels, a step A of the electrode film portion (1000 Å to 3000 Å) is formed between the substrate surface and the electrode surface, and when alignment control is performed using the temperature cooling process. The above-mentioned step A causes an alignment defect in the ferroelectric liquid crystal 17 by using the step A as a bulge. Furthermore, when the alignment control films 15 and 16 are provided on the substrates 11 and 12, where the step A exists, respectively, a step B formed in accordance with the step A is also formed in the alignment control film almost at the film portion of the electrode. , alignment defects were produced in the ferroelectric liquid crystal 17 as described above.

Figure 2 is a sketch of the ferroelectric liquid crystal element shown in the above-mentioned comparative example when observed with a crossed Nicol polarizing microscope.
8), a line 22 is observed corresponding to the step B on the substrate 11 in FIG. 1, and a line 1/s23 is observed corresponding to the step B on the substrate 12 in FIG. Also, a portion 24 in the figure is a ferroelectric liquid crystal sandwiched between opposing electrodes. A large number of edge-like lines 25 appearing in the polarizing microscope represent alignment defects in the ferroelectric liquid crystal.

If a step of 1.000 Å or more exists in the contacting surface of the ferroelectric liquid crystal in this manner, alignment defects will occur from the step, and the formation of monodomains of the ferroelectric liquid crystal will be inhibited.

Figure 3 (A) is a sectional view of a preferred ferroelectric liquid crystal element of the present invention, and Figure 3 (B) is a perspective view showing an embodiment of a single-sided substrate used in this element.

The device 30 shown in FIG. 3 has substrates 31 and 32 made of transparent plates such as glass plates or plastic plates, and a ferroelectric liquid crystal 33 is sandwiched between them. Each board 31 and 3
2 is a striped electrode that forms a matrix electrode structure! 34 and 35 are wired, respectively.

The substrate 31 has a structure as shown in FIG. 3(B).

That is, electrode lines 34 necessary to form a matrix electrode structure are arranged in a stripe shape on the substrate 31, and an alignment control film 36 that covers the substrate 31 itself and the electrode lines 34 is provided integrally with a spacer member 38. ing. At this time, after forming a thick film of an insulating material over the entire surface of the substrate 31 on which the electrode 34 is provided using a method such as a spinner coating method, etching is performed using a predetermined photolithography technique except for the spacer member 38. By doing so, the alignment control film 36 and the spacer member 38 can be integrated, and the alignment control film 36 can be formed as a leveling layer, which eliminates the step difference that was the problem mentioned above. can do. The alignment control film 36 is generally set in the range of 10 Å to 1 μm, preferably 10 Å to 3000 μm, although it depends on the thickness of the ferroelectric liquid crystal. The thickness of the spacer member 38 can determine the thickness of the ferroelectric liquid crystal 33, so it varies depending on the type of liquid crystal material and the required response speed, but it is generally 0.2μ.
~20μ, preferably in the range of 0.5μ to 10μ.

It is preferable that an orientation control M37 covering the substrate itself and the electrode 35 is also formed on one side of the substrate 32. In this case, the orientation control film 37 can be formed as a flattened layer by forming a thick film of an insulating material using a method such as a spinner coating method, and then uniformly etching the entire surface. . Further, a spacer member can be formed on this substrate 32 as needed, but in this case, this spacer member is formed on the substrate 31 described above.
can be obtained in the same way as in the case of .

The flattening layer used in the present invention is a film that is thick enough to hide the level difference that occurs between the electrode surface and the substrate surface, and is made of an insulating material (especially a resin that can be used for the spacer member and alignment control film to be lowered). ) is formed by a method such as a spinner coating method, and then etched to a predetermined thickness by a uniform dry etching method such as plasma etching. For example, the step mentioned above is 100
If the insulating material is coated with a thickness of 2μ or more, preferably 5μ or more using a spinner coating method, the level difference on the surface of this film can be reduced to 500λ or less, and this film can be further dried. By etching, the level difference on this surface is flattened to about 300 Å to 500 λ, and the level difference occurring between the electrode surface and the substrate surface can be sufficiently hidden.

In the present invention, the above-mentioned flattening layer has a step difference between the coating surface covering the substrate itself and the coating surface covering the electrode portion.

It can be set to λ or less, preferably 500λ or less. This level difference is 1000λ or more, especially 1
A liquid crystal element using a non-flattened layer formed with a thickness of 200λ or more will cause alignment defects of edge lines as shown in the above-mentioned FIG. 2 or the comparative example below.

Etching gases for plasma etching used when forming the flattening layer of the present invention include O, CO, , which are capable of etching organic substances even when used alone.
Ashing gas such as H,,N, etc.
Rare gases such as Xe and CF', which produces desirable properties when added to these gases.

CtFs, C5Fa, CHF', etc. 77 carbon SiF'a, XeF, etc.

A mixture of a fluorine-based gas made of other heptafluoride compounds such as NFIl or a chlorine-based gas made of a chlorine-containing compound such as Cet, CCe, BCes, etc. is suitable.

A specific example is 20. A mixed gas consisting of cO and CF4, a mixed gas consisting of cO and CF, 0. and ccg.

A mixed gas consisting of Ar and CF4, N
, and CF4.

The amount of fluorine gas or chlorine gas added is in the range of 0.1 to 45%, preferably 20 to 30%, based on the total volume. If the amount added is less than 0.1%, the effect of addition will not be sufficient, and if it is more than 45%, the characteristics of the ashing gas or noble gas will not be sufficiently improved, which is not preferable.

In addition, examples of materials for the alignment control films 36 and 37 include:
For example, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide.

Resins such as polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin,
Alternatively, it can be formed by selecting from photosensitive polyimide, photosensitive polyamide, cyclized rubber photoresist, phenol novolak photoresist, or electron beam photoresist (polymethyl methacrylate, epoxidized-1,4-polybutadiene, etc.). preferable.

Furthermore, the liquid crystal element of the present invention can also be applied to a system in which pixels are switched using thin film transistors. That is, pixel electrodes and thin film transistors are arranged in an array on a substrate, and a flattening layer is formed thereon in the same manner as described above, and this flattening layer functions as an alignment control film. Accordingly, a monodomain ferroelectric liquid crystal layer without alignment defects can be formed.

This method of switching ferroelectric liquid crystal pixels using thin film transistors is suitable for high-definition displays, and can reduce the number of wiring lines.

In another preferred embodiment of the present invention, the occurrence of alignment defects that appear in ferroelectric liquid crystals can be improved by using a liquid crystal element having a leveling layer shown in FIGS. 4 and 5.

FIG. 4(A) is a sectional view of another liquid crystal element of the present invention, and FIG. 4(B) is a perspective view of a portion thereof. The liquid crystal element shown in FIG. 4 includes substrates 41 and 42 made of glass or plastic plates, and a group of electrodes 4 formed in a predetermined pattern (stripe shape in this example) by etching or the like.
3 and 44 (for example, a matrix electrode structure) are formed. These electrode groups 43 and 44 (441°442)
Alignment control films 45 and 46 are formed covering the electrodes 441 and 442, and a stripe-shaped spacer member 48 for setting the layer thickness of the liquid crystal 47 is formed over the entire interval between the electrodes 441 and 442.

The stripe-shaped spacer 48 is formed by applying an electrically insulating material to a thickness required for the liquid crystal layer by spinner coating or the like, and then photo-etching the material so that the stripe spacer member 48 is placed in the interval between the electrodes. It can be formed by doing the following. Orientation control films 45 and 4
6, a thin film can be formed on each of the electrode groups 43 and 43 by spinner coating.

The transparent film thickness of the alignment control films 45 and 46 depends on the thickness of the liquid crystal layer 47, and is usually set between 10 to 1 μm, preferably 100 Å to 3000 μm.

Materials for this alignment control film include, for example, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, and cellulose resin. , resins such as melamine resin, urea resin, acrylic resin, or photosensitive polyimide, photosensitive polyamide, cyclized rubber photoresist, phenol novolac thread photoresist, or doublet beam photoresist (polymethyl methacrylate, epoxidized-1 , 4-polybutadiene, etc.).

The thickness of the liquid crystal layer depends on the ease of alignment specific to the liquid crystal material and the response speed required for the device, but is determined by the height of the spacer member, and is usually 0.2μ to 200μ, preferably 0.2μ. It is set in the range of 5μ to 10μ.

FIG. 5 shows a modification of the liquid crystal element shown in FIG. 3, in which a spacer member 38 is formed to the inside of striped electrode lines 341 and 342. In the figure, the same reference numerals as No. 3M represent the same members.

FIG. 6 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal. 61 and 61' are In,
O,, SnO2 or ITO (Indium-Tin
It is a substrate (glass plate) coated with a transparent '+11 electrode made of thin IJI such as (Oxide), between which the liquid crystal molecular layer 62 is oriented perpendicularly to the glass surface and is made of SmC" phase or 8 m H" phase. Liquid crystal is enclosed.

A thick line 63 represents a liquid crystal molecule, and this liquid crystal molecule 63 has a dipole moment (P±) 64 in a direction perpendicular to the molecule. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 61 and 61', the liquid crystal molecules 6
The helical structure of 3 unravels, dipole moment) (P soil) 6
The alignment direction of the liquid crystal molecules 63 can be changed so that all of the liquid crystal molecules 63 are oriented in the direction of the electric field. The liquid crystal molecules 63 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. Therefore, for example, if cross-niffle polarizers are placed above and below the glass surface, the polarizer will change depending on the voltage applied polarity. It is easily understood that this results in a liquid crystal optical modulation element whose optical properties change.

The liquid crystal cell preferably used in the liquid crystal element of the present invention can have a sufficiently thin thickness (for example, 10 μm or less). As the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure even when no electric field is applied, as shown in Figure 7, and its dipole moment P or P' is directed upward ( 74) or downward (
74'). In a cell like this,
As shown in FIG. 7, when electric fields E or E' of different polarities above a certain threshold are applied by voltage application means 71 and 71',
The dipole moment changes its direction upward 74 or downward 74' in response to the electric field vector of the electric field E or E', and depending on the direction, the liquid crystal molecules are in the first stable state 73 or in the second stable state 73. Orientation to one of the stable states 73'.

As mentioned above, there are two advantages to using such ferroelectricity as a liquid crystal element. The first is that the response speed is extremely fast, and the second is that the alignment of liquid crystal molecules has bistability. To further explain the second point with reference to FIG. 7, for example, when an electric field E is applied, the liquid crystal molecules
This state is stable even when the electric field is turned off. When an electric field E' in the opposite direction is applied, the liquid crystal molecules are oriented to a second stable state 73' and change their orientation, but they remain in this state even after the electric field is turned off. Also, as long as the applied electric field E does not exceed a certain threshold,
They are still maintained in their respective orientation states. In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible.

8 to 10 show examples of driving the liquid crystal element of the present invention.

Figure 8 shows a matrix with a ferroelectric liquid crystal compound sandwiched in the middle.
FIG. 8 is a schematic diagram of a cell 81 having an IJ square electrode structure. 8
2 is a scanning electrode group, and 83 is a signal electrode group. 9th
Figures (a) and (b) respectively show selected scan' electrodes 8.
2 (electrical signal given to sl and other scanning electrodes (
9(C) and (d) show the electrical signals applied to the selected signal electrode Sa(S) and the unselected signal electrode 83(n), respectively. n) represents an electrical signal applied to In FIGS. 9(a) to 9(d), the horizontal axis represents time and the vertical axis represents voltage. For example, when displaying a moving image, the scanning electrode groups 82 are sequentially and periodically selected. Now, let us assume that the dark value voltage for providing the first stable state of the liquid crystal cell having bistable property is vthl, and the threshold voltage for providing the second stable state is -Vth. As shown in FIG. 9(a), the electrical signal applied to S) is an alternating voltage such that it is V at phase (time) 11 and -■ at phase (time) t.

Further, the other scanning electrodes 82(n) are in a grounded state as shown in FIG. 9(b), and have an electric signal O.

On the other hand, the electrical signal given to the selected signal electrode 83(s) is V as shown in FIG. 9(C), and the electrical signal given to the unselected signal electrode 83(n) is V as shown in FIG.
As shown in Figure (d), <-V. In the above, the voltage V is set to a desired value that satisfies V(Vth, < 2 V to V > - Vth, > - 2 V. When such an electric signal is applied, each pixel The applied voltage waveform is the 10th
As shown in the figure. 10(a) to (d) correspond to pixels A, B, C, and D in FIG. 8, respectively. That is, as is clear from FIG. 10, for the pixels on the selected scanning line, a voltage 2<b>2 that exceeds the threshold value v th is applied at phase t. Also, for pixel B existing on the same scanning line, the phase is 1. The voltage that exceeds the threshold value -vth at -2V
is applied. Therefore, the signal on the selected scanning electrode line! Depending on whether a pole is selected or not, if selected, the liquid crystal molecules are aligned in the first stable state, and if not selected, the liquid crystal molecules are aligned in the second stable state. In any case, it has nothing to do with the previous history of each pixel.

On the other hand, as shown in pixels C and D, on unselected scanning lines, the voltage applied to all pixels C and D is +V or -■, neither of which exceeds the threshold voltage. Therefore, the liquid crystal molecules in each pixel C and D maintain the orientation corresponding to the signal state when scanned last time without changing the orientation state. That is, when a scanning electrode is selected, a signal for that one line is written, and -
The signal state can be maintained until the next selection after the end of the frame. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change, and contrast reduction and crosstalk do not occur at all. On this occasion,
The value of the voltage value (■) and the value of the phase (t, +t,) = T depend on the liquid crystal material used and the thickness of the cell, but are usually 3 volts to 70 volts and 0.1 μsec to 2 m s.
A range of ec is used. Therefore, in this case, the electrical signal applied to the selected scanning electrode is in the first stable state (
any change from a stable state (supposed to be a "bright" state when converted to an optical signal) to a second stable state (supposed to be a "dark" state when converted to an optical signal), or vice versa. I can wake up.

FIG. 11 shows another preferred embodiment of the liquid crystal element of the present invention. In the moving image display liquid crystal display element shown in FIG. 11, liquid crystal cells 111 similar to those shown in FIGS. 3 to 5 are arranged.

On both sides of this liquid crystal cell, linear polarizers 113 and 114 are arranged in a crossed nicol state, and behind the linear polarizer 114 is a reflector (aluminum evaporation or diffuse reflector - aluminum evaporation film with a matte surface). (not shown).

A liquid crystal cell having these configurations is sandwiched between a pair of glass plates 115 provided with a Nesa film 116, and by passing a current through the Nesa film 96 using a heating power source 117,
It is possible to control the temperature of the liquid crystal cell 111. At this time, the liquid crystal cell 111 is connected to the scanning signal source 118.
and the signals applied to the information signal source 119.

Hereinafter, the present invention will be explained according to examples.

Example 1 ITO striped electrode pattern (10p) with a film thickness of 1200λ and a line width of 80μ formed at a pitch of 20μ
A polyimide forming solution (rPIQ manufactured by Hitachi Chemical Co., Ltd. with a non-volatile content concentration of 14.5
wt, %) was applied for 30 minutes using a spinner coater rotating at 300 Orpm, and heated at 120"O for 30 minutes to form a 2μ y IJ imide coating. Then,
Positive resist solution (“AZ13” manufactured by Shipley)
50"1) was applied with a spinner and prebaked. On this resist layer, the mask width was 8μ and the pitch of the mask portion was 1.OOμ so that the mask was located near the middle between the TO electrode lines.
It was exposed using a striped mask. Next, by developing with a developer "MF312" 1, the exposed portions of the resist film were removed by etching. After that, the polyimide film in the non-mask area is incinerated to a film thickness of 1000 nm by plasma etching using an etching gas that is a mixture of O gas and CF gas at a flow rate ratio of 3:1 per unit time. This was removed to form a flattened layer that was integrated with the spacer member. Thereafter, the resist mask was removed, and the polyimide film was completely cured by heating at 200'O for 60 minutes and then at 350°C for 30 minutes, and was rubbed in a direction parallel to the spacer member to create an electrode plate (A). .

On the other hand, with a film thickness of 1200 people and a line width of 80μ, the pitch is 2.
A polyimide film with a thickness of 1000λ was formed on a glass plate having an ITO stripe electrode pattern formed with a thickness of 0 μm in the same manner as described above, except that one photolithography step was omitted, and then rubbed ( B) An electrode plate was created.

The surface conditions of the electrode plate (A) and the electrode plate (B) produced in this manner were measured using a universal surface profile measuring device 1'-8 manufactured by Koita Institute.
When measured by E-3CJ, the difference in level between the polyimide film surface corresponding to the electrode portion and the polyimide film surface corresponding to the non-electrode portion of each electrode plate was approximately 400 Å to 500 Å.

(A)! The cell was assembled so that the striped pattern electrodes of the electrode plate and the (B) electrode plate were perpendicular to each other and the rubbing directions were parallel to each other, and DOBAMBC was heated until it became a 1sotropic phase and sealed in the cell.

The temperature of the cell was gradually cooled, and a monodomain liquid crystal device was completely fabricated. When this liquid crystal element was observed under a crossed nicol polarization microscope, it was found that there was no alignment defect of the edge lines that appeared in the comparative example below.

Incidentally, the above-mentioned "PIQ" represents polyimide isoindoquinazolinedione.

Comparative Example 1 An ITO pattern with a thickness of 1200λ was prepared in the same manner as in Example 1! 1! A 2μ thick polyimide film was formed on the electrode plate.

Next, the same positive resist solution as in Example 1 (5hi
"AZ1350"' manufactured by Pley was coated with a spinner and prebaked. On this resist layer, a mask width of 8 μm is applied.
, M light was emitted using a striped mask with a pitch of 100 μm. Next, by developing with a developer containing tetramethylammonium hydroxide "MP312'', the entire thickness of the resist film in the exposed area and the underlying polyimide film is etched. After washing with water and drying, the resist film is removed. The mask film was removed. After that, 2
The material was cured by heating at 00"O for 60 minutes and at 350°C for 30 minutes to form a spacer member.

After that, a film of PIQ similar to that described above was formed to a film thickness of 1000λ, and then heated under the same conditions as described above.
The surface was rubbed in a direction parallel to the spacer member (an A0 electrode plate was created).

Next, an electrode plate (B') was produced in the same manner as described above, except that the step of forming the spacer member used in producing the electrode plate (A') described above was omitted.

When the surface conditions of the (A0 electrode plate and (B') electrode plate) created in this way were measured in the same manner as in Example 1, it was found that 1
There was a gap of 200 people.

A liquid crystal device was prepared using these electrode plates in the same manner as in Example 1, and when observed with a crossed Nicol polarizing microscope, it was found that many alignment defects of the edge-like lines shown in FIG. 2 were formed. There was found.

Example 2 The film thickness is 1500, the line width is 50μ, and the pitch is 12.5.
ITO stripe electrode pattern (16
PET used in Example 1 on a glass plate with PET
IQ was applied to a thickness of 2 μm to form a polyimide film.

Next, after forming the resist layer used in Example 1 on this polyimide film, ■ mask width 12.5μ so that the mask is located on the entire surface between the TO electrodes, the pitch of the mask part 50μ
It was exposed using a striped mask. Next, the resist film and polyimide film in the exposed areas are removed by developing with a developer containing tetramethylammonium hydroxide "MF312", and then the resist mask is removed and the film is heated and cured under polyimide curing conditions. A spacer member having a shape that completely covered the space between the TO electrode wires was formed.

Next, on the substrate on which the spacer member was formed, a film of PIQ similar to that described above was formed to a thickness of 1000 ml and cured under predetermined curing conditions to form a flattened layer made of a polyimide film. After binding, the surface of the polyimide film was rubbed in a direction parallel to the stripe spacer member to obtain an electrode plate (C).

On the other hand, with a film thickness of 1,500 and a line width of 50μ, the pitch is 1.
10μ of PIQ used in Example 1 was placed on a glass plate having an ITO stripe electrode pattern formed with a thickness of 2.5μ.
A thick coating was applied to form a polyimide film. Next, this polyimide film was ashed and removed by plasma etching using the same etching gas as in Example 1 until the film thickness reached 1000 nm. After that, this surface is rubbed (D) 't4! It was used as a pole plate.

When the surface condition of the polyimide film formed on these electrode plates was measured in the same manner as in Example 1, (C)′IL
As for the electrode plate, there is no substantial difference in level because the spacer member is arranged over the entire interval between the electrode wires a4ff.
Also, in (D) the electrode plate, the level difference between the polyimide film surface of the electrode part and the polyimide film surface of the non-electrode part is approximately 300 Å to 600 λ.
It was about.

The cell was assembled so that the striped pattern electrodes of the (C) electrode plate and the (D) electrode plate were perpendicular to each other and the rubbing directions were parallel to each other, and DOBAMBC was heated until it became a 1sotropic phase and sealed in the cell.

The temperature of the cell was gradually cooled, and a monodomain liquid crystal cell was fabricated.

When this liquid crystal element was observed using a crossed Nicol polarizing microscope, it was found that no alignment defects were observed as in the above-mentioned comparative example.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional ferroelectric liquid crystal element. FIG. 2 is an explanatory diagram showing stitches when a conventional ferroelectric liquid crystal element is observed with a crossed Nicol polarizing microscope. FIG. 3(A) is a sectional view of the ferroelectric liquid crystal element of the present invention, and FIG. 3(B) is a perspective view of one side of the substrate. Figure 4 (A
) is a sectional view of another ferroelectric liquid crystal element of the present invention, and FIG. 4(B) is a perspective view of one side of the substrate. FIG. 5 is a perspective view of another ferroelectric liquid crystal element of the present invention. 6 and 7 are perspective views schematically showing the ferroelectric liquid crystal used in the present invention. FIG. 8 is a plan view showing the IJ electrode structure used in the present invention. 9(al) to (d) are explanatory diagrams showing signals for driving the liquid crystal element of the present invention. FIG. 10(a) to (dl) show voltage waveforms applied to each pixel. It is an explanatory diagram. Fig. 11 is a sectional view showing an embodiment of the present invention. Patent applicant: Canon Inc. (CoCI)) (d-) (shi) (C) tl-t (d) --------Vt/Lz Procedural amendment blind motion) May 16, 1985 Patent Application No. 269886 of 1988 2, Title of Invention Liquid Crystal Element 3, Person Who Makes Amendment Case Relationship Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4. Agent's residence: Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo 146 (telephone: 758-2111). 5. Date of amendment order (shipment date): April 30, 1985. 6. Subject of amendment. Specification 7, Contents of amendment (1) rM on page 3, lines 7 to 12 of the specification, 5ch
adt---(twisted nematic)J
“M, C?-/T (M, 5chadt) and W, Helfrich, “Applied Physics Letters Volume 18,
Number 4 (1,971, 2, 15), page 127~
128 (“Applied Physics Le
tters'' Vo, 18, Th, 4 (1
971, 2, 15) P, 127-128) “Voltage Dependent Optical Activity”
e of a twisted nematic liquid crystal” (“Voltage I)”
t 0ptical Activity of aTw
isted Nematic Liquid Crys
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)) Correct it as J. LE JOURNAL ICE
P) IYsIQUE l, ETTER3) Se16 (L -69) 1975. rFerroelectric Liquid Crystals J
ctric RequestedGrystalsJ)
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“Applied Physics Letters”
)1dan(11). +98Or Zabmicro Fist Second Bistiple Electro-Optic Switching in Liquid Crystals J (Snbmicro 5econ
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sJ); Correct as J.

Claims (10)

[Claims] (1) In a liquid crystal element having a ferroelectric liquid crystal between a pair of parallel substrates, at least one of the pair of parallel substrates has an electrode, and a flattening layer covering the substrate and the electrode is provided. 1. A liquid crystal element comprising: the ferroelectric liquid crystal disposed in contact with a surface of a flattening layer. (2) The liquid crystal element according to claim 1, wherein the electrode is formed of a transparent conductive film having a thickness of 1000 Å to 3000 Å. (3) The liquid crystal element according to claim 1, wherein the flattening layer is a flattening film in which the distance between the coating surface covering the substrate itself and the coating surface covering the electrode portion is 1000 Å or less. (4) The liquid crystal element according to claim 1, wherein the flattening layer is a flattened film having a distance of 500 Å or less between the film surface covering the substrate itself and the film surface covering the electrode portion. (5) The liquid crystal element according to claim 1, wherein the leveling layer is formed of an insulating material. (6) The liquid crystal element according to claim 1, wherein the leveling layer has a function as an alignment control film. (7) The liquid crystal element according to claim 1, wherein the flattening layer is integrally formed with a spacer member. (8) The liquid crystal device according to claim 1, wherein the ferroelectric liquid crystal is a chiral smect liquid crystal. (9) The chiral smectate liquid crystal has a C phase, an H phase,
9. The liquid crystal element according to claim 8, which is an I-phase, J-phase, K-phase, G-phase or F-phase. (10) The liquid crystal device according to claim 8, wherein the chiral smect liquid crystal has a non-helical structure.